Stylus with Intermittent Voltage Driving and Sensing

1. A stylus device for interacting with a computer, the stylus device comprising, an operational circuit, an operational switch for activating and deactivating the operational circuit, a driving and sensing circuit configured for driving a voltage supply to the operational circuit and sensing a state of the operational switch, and a controller for transmitting synchronized control signals to the driving and sensing circuit for intermittently or periodically executing the sensing at a pre-defined time in relation to the driving, wherein the sensing is executed via a same electrical conductor as the driving.

2. The device of claim 1 , wherein the operational circuit is an eraser circuit.

3. The device of claim 1 , further comprising a writing tip, and a writing tip driving circuit configured for driving a voltage supply to the writing tip.

4. The device of claim 3 , wherein the operational switch is opposite to the writing tip.

5. The device of claim 1 , wherein the driving and sensing circuit is configured for sensing a voltage on the electrical conductor, and transmitting a signal indicating the state of the operational switch in response to the sensing.

6. The device of claim 1 , further comprising a resistive electronic element forming a resistance path from the electrical conductor to a reference point via the operational switch.

7. The device of claim 6 , wherein the driving and sensing circuit is configured for sensing a voltage drop on the electrical conductor when current flows through the resistance path, and transmitting a signal indicating that the operational switch is closed in response to the sensing.

8. The device of claim 1 , further comprising a capacitive electronic element forming a capacitance path from the electrical conductor to a reference point via the operational switch.

9. The device of claim 8 , wherein the driving and sensing circuit is configured for sensing a voltage drop on the electrical conductor when the capacitive electronic element is charged, and transmitting a signal indicating that the operational switch is closed in response to the sensing.

10. The device of claim 1 , wherein the sensing is executed at a peak of the driving.

11. The device of claim 1 wherein the sensing is executed after a peak of the driving.

12. The device of claim 1 , wherein the sensing is executed before a peak of the driving.

13. The device of claim 1 , wherein said driving comprises boosting.

14. A method of operating an electronic circuit requiring a voltage drive, the electronic circuit being associated with an operational switch for activating and deactivating the electronic circuit, the method comprising: driving a voltage supply to the electronic circuit via an electrical conductor; sensing a state of the operational switch via said electrical conductor; and synchronizing control signals to intermittently or periodically execute the sensing on the same said electrical conductor as the driving at a pre-defined time in relation to the driving.

15. The method of claim 14 , wherein the sensing comprises sensing voltage on a resistance path between the electrical conductor and reference point.

16. The method of claim 14 , wherein the sensing comprises sensing voltage on a capacitance path between the electrical conductor and a reference point.

17. The method of claim 14 , wherein the sensing is executed at a peak of the driving.

18. The method of claim 14 , wherein the sensing is executed after a peak of the driving.

19. The method of claim 14 , wherein the sensing is executed before a peak of the driving.

20. A method of communicating with a computer having a touch screen, the method comprising forming a pattern over the touch screen using a stylus device, the stylus device having an operational circuit, an operational switch for activating and deactivating the operational circuit, a driving and sensing circuit configured for driving a voltage supply to the operational circuit and sensing a state of the operational switch, and a controller for transmitting synchronized control signals to the driving and sensing circuit for intermittently or periodically executing the sensing at a pre-defined time in relation to the driving, the sensing being executed via a same electrical conductor as the driving.